public class TicketSystem  {
    private DiscountStrategy discountStrategy;

    public void setDiscountStrategy(DiscountStrategy discountStrategy) {
        this.discountStrategy = discountStrategy;
    }

    public double calculateDiscountedPrice(double originalPrice) {
        if (discountStrategy != null) {
            return discountStrategy.calculateDiscountedPrice(originalPrice);
        }
        return originalPrice;
    }
}